Monolithically integrated thin-film device with a solar cell, an integrated battery, and a controller

ABSTRACT

A thin-film monolithically integrated solar module with a solar cell, an integrated energy storage device, and a controller may be provided. It may comprise a thin-film solar cell, having at least one solar diode, on a transparent substrate, a thin-film energy storage device, and an electronic controller comprising at least one thin-film transistor above the thin-film energy storage device. The electronic controller may be electrically connected to the thin-film solar cell and the thin-film energy storage device by vias. The named functional units may build a monolithically integrated device on one substrate.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to United Kingdom Patent ApplicationNo. GB1400531.8, filed Jan. 14, 2014, which is incorporated herein inits entirety.

BACKGROUND OF THE INVENTION

The invention relates generally to an integrated thin-film device with asolar cell, an integrated battery and an electronic controller. Theinvention relates further to a method for manufacturing a relatedmonolithically integrated device. Solar cells are photovoltaic deviceswhich convert sunlight into electricity.

Solar cells are either made of crystalline silicon wafers or are basedon thin-film silicon technologies. Alternatively, solar cells may bebased on amorphous silicon. Other alternatives may be based on CIGS(Copper-Indium-Gallium-(Di-(Selenide)), CdTe (Cadmium-Telluride) or CZTS(Copper-Zinc-Tin-Sulfide). Solar cells are used in a wide range ofapplications. They may, e.g., be used to deliver power into a publicpower grid, recharge batteries in remote locations, recharge mobiledevices like mobile telephones, or may function as a sole energy sourcefor pocket calculators. One key design parameter for solar cells is theproduction price in relation to the efficiency of the conversion processfrom light energy to electrical energy.

One problem of solar cells is their direct dependence on incoming light.In order to charge batteries efficiently using solar cells, additionalelectronic components may be required. The electronic components orcircuits may be used to transform and reshape the output voltage ofsolar cells or solar cell modules comprising several solar cells.Individual solar cells have non-linear output efficiency due to therelationship between solar radiation, temperature, and total resistance.

To maximize power output of a solar cell module, solar cell arrays mayuse one or many different maximum power point tracking (MPPT)techniques. Such devices are typically integrated into a power convertersystem which provides voltage or current conversion, filtering, andregulation for driving various loads in power grids and batteries. Inorder to keep price points for production low, solar cells may beintegrated with these required additional electronic components.

On the other side, there have been approaches to integrate a solar cellwith a prefabricated battery. Such an approach has been described in US2009/0288700 A1. The document relates to an integrated device comprisingat least one inorganic photovoltaic cell, a substrate supporting theinorganic photovoltaic cell, a prefabricated battery coupled to the atleast one inorganic photovoltaic cell, and an encapsulation for sealingthe integrated device.

Additionally, US 2012/0043814 A1 discloses an integrated photovoltaicelectronic cell and battery device. The integrated device includes aphotovoltaic cell, a battery, and interconnects providing athree-dimensional integration of the photovoltaic cells and the batteryinto an integrated device for capturing and storing solar energy.

However, there remains a need to produce high quality thin-film solarmodules at low prices ensuring a long life of integrated batteries andeasy connectivity to a power grid or other power consumers.

SUMMARY

This need may be addressed by a thin-film integrated device with a solarcell, an integrated battery and a controller and method formanufacturing an integrated device with a solar cell, an integratedbattery and a controller according to the independent claims.

According to one aspect, a thin-film integrated device with a solarcell, an integrated energy storage device and a controller may beprovided. The thin-film solar module may comprise a thin-film solarcell, having at least one solar diode, on a transparent substrate, athin-film energy storage device above the thin solar cell, and anelectronic controller comprising at least one thin-film transistor abovethe thin-film energy storage device. Thereby, the electronic controllermay be electrically connected to the thin-film solar cell and thethin-film energy storage device through vias. The thin-film solar cell,the thin-film energy storage device and components of the electroniccontroller may build a monolithically integrated device, i.e., allelements may be built on one substrate.

According to a different aspect, a method for manufacturing a thin-filmsolar module in a superstrate configuration may be provided. The methodmay comprise building a thin-film solar cell, having at least one solardiode, on a transparent substrate; building a thin-film energy storagedevice above the thin solar cell; and building an electronic controllercomprising at least one thin-film transistor above the thin-film energystorage device.

The method may further comprise providing electrical connections betweenthe electronic controller, the thin-film solar cell and the thin-filmenergy storage device by vias. Thus, the superstrate configuration maybe built in an integrated thin-film manufacturing process building amonolithically integrated device.

It may be noted that no external elements may be required for a fullyfunctional monolithically integrated solar module. The monolithicallyintegrated solar module may have all required components on board oron-chip.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way ofexample only, and with reference to the following drawings:

FIG. 1A depicts a thin-film solar module in accordance with anembodiment of the present invention.

FIG. 1B depicts a thin-film solar module with different vias inaccordance with an embodiment of the present invention.

FIG. 2 depicts the thin-film solar cell and the thin-film battery inaccordance with an embodiment of the present invention.

FIG. 3 depicts additional layers of the solar cell module, in particulara second dielectric layer and a first structured metal layer inaccordance with an embodiment of the present invention.

FIG. 4 depicts a third dielectric layer and a structured semiconductorlayer in accordance with an embodiment of the present invention.

FIG. 5 depicts examples of vias within the superstrate device inaccordance with an embodiment of the present invention.

FIG. 6 depicts a second metal layer connecting individual devices of theintegrated solar cell module in accordance with an embodiment of thepresent invention.

FIG. 7 depicts electronic circuitry functioning as electronic controllerin accordance with an embodiment of the present invention.

FIG. 8 depicts a top view of the second metal layer, including aconnected inductor, in accordance with an embodiment of the presentinvention.

FIG. 9 depicts an extended solar module comprising a series of solarcell modules and electronic controllers in accordance with an embodimentof the present invention.

FIG. 10 depicts a configuration of two combined solar cell modules inaccordance with an embodiment of the present invention.

DETAILED DESCRIPTION

In the context of this description, the following conventions, termsand/or expressions may be used:

The term energy storage device may denote a device capable of storingelectrical energy. It may either be a battery, e.g., a Lithium basedbattery, or a super-capacitor. Such a super-capacitor may be charged bya solar cell. Afterwards, it may be discharged, e.g., powering electricor electronic components or delivering its energy to a DC bus.

The term integrated device may denote a device which may integrateseveral functional units—e.g., a solar cell, an energy storage device aswell as active and passive electronic components on one substrate. Noprefabricated sub-elements may be required. Every component may be builtas part of a three-dimensional stack of functional units.

The proposed thin-film integrated device with a solar cell, anintegrated battery, and a controller, and the related manufacturingmethod, may offer a couple of advantages:

With the integration of a thin-film energy storage device, a thin-filmcontrol electronic device and a thin-film solar cell into one solar cellmodule, the size of the integrated device incorporating all elements canfurther be reduced if compared to the state of the art. No additionaloutside wiring between the solar cell, the battery, and/or an electroniccircuit may be required. Even if two components—e.g., the solar cell andelectronic circuit or, the solar cell and a prefabricated battery—may beintegrated, the space requirements and production cost are higher ifcompared to the integrated proposed solar cell module. Additionally,existing technology does not allow integrating all three functionalunits into one device which may be manufactured in one integratedthin-film fabrication process. Consequently, prices for providing allthree functionalities in one monolithically integrated solar cell modulemay be reduced. Moreover, the reliability of such device may beincreased if compared to individually manufactured components. This maylead to more competitive offerings.

Such integrated thin-film solar modules may also be a basis forcompletely autonomous sensors. The battery may be charged duringdaylight time and may deliver enough energy through the battery at nighttime for keeping a non-wired sensor operational during day and night.Signals to and from the sensor may be transmitted wirelessly. This way,an Industry 4.0 scenario may easily be built. Measurement values ofenvironmental parameters may be collected without any wiringrequirements and without any battery exchange requirements. Theintegrated sensors may be operational continuously, i.e., 24 hours aday, 7 days a week, without any maintenance and/or battery exchange.

Additionally, the integrated electronic circuits may comprise a maximumpower point tracking circuitry in order to deliver a maximum output ofelectrical energy of solar cell arrays. If a series of solar cells maybe connected in series, i.e. a solar cell string, in order to achieve agiven output voltage, the solar cell in the string having the worstperformance may reduce the overall efficiency of the solar cell string.The integrated power conversion electronics as part of the electroniclayer of the disclosed thin-film solar module may guarantee a maximumpower output of a system of thin-film solar modules.

Lithium based batteries may be used as energy storage devices. However,as known by a skilled person, Lithium batteries may not be exposed tohigh temperatures during manufacturing, requiring a process sequence toprotect the battery from high temperatures. This generally excludes hightemperature annealing steps after the deposition of the battery layers.However, as proposed here, an oxide semiconductor may be formed at ornear room temperature and hence, may be fabricated after a deposition ofthe energy storage device. Thus, generally, the temperature required formanufacturing the superstrate configuration of the proposed thin-filmsolar module decreases from layer to layer.

The integrated controller may have different functions. It may functionas a controlling circuit, enabling a connection of the solar module or aseries of solar cells to a power grid. The output of the solar cell mayalso be converted by the electronic controller to ensure the rightvoltage and/or—in case of AC (alternative current)—the right frequency.

Alternatively, the energy storage device may be connected to the powergrid during times the solar cells do not deliver energy. Here, aconversion may be possible using the electronic controller. Many activeand passive electronic components may be integrated into the layer ofthe electronic controller.

As additional function, the electronic controller may control theloading of the energy storage device via the solar cell of the solarmodule. Overcharging may be avoided and the electronic controller mayguarantee the right voltage and current for the loading of the energystorage device. The electronic controller may also control a connectionbetween the solar cell, or the energy storage device, and the DC bus.

The solar module may be enhanced by additional features which may now bediscussed:

According to one embodiment of the thin-film solar module, the thin-filmsolar cell may comprise a transparent front-side electrode atop thetransparent substrate, a photovoltaic layer atop the front-sideelectrode, and a back-side electrode atop the photovoltaic layer. Theactive parts, i.e., the photovoltaic layer of the solar cell, maycomprise an n-type oxide semiconductor, a buffer layer, an absorbermaterial. The back-side electrode may comprise metal like, e.g., Mo, Cu,Al, Ag or other suitable metals, or alloys. The front-side electrode maybe built from TCO (transparent conductive oxide).

In one embodiment of the thin-film solar module, a first dielectriclayer may be comprised atop the back-side electrode of the solar cell.It may build an isolating layer between the thin-film solar cell and thenext functional unit, e.g., the energy storage device.

According to one embodiment of the thin-film solar module, the thin-filmenergy storage device may comprise a lower electrode, e.g., forming ancathode, atop the first dielectric layer, an active energy storage layeratop the lower electrode, and an upper electrode (134), in particularforming an anode, atop the active energy storage layer. The cathode andthe anode may also be built the other way around.

The thin-film energy storage device may comprise several layers ofthin-film energy storage devices, one atop the other. These may comprisea hybrid device, i.e. stacked super-capacitors with stacked batteries.

According to one advantageous embodiment of the thin-film solar module,the active energy storage layer may comprise a cathode layer, inparticular LiMn-Oxide, a solid electrolyte layer and an anode layer, inparticular metallic Lithium or a Li-Carbon-compound. These Li-comprisinglayers may be directly integrated in-between the solid electrolyte andthe upper and lower electrode establishing electrical contact to them.

According to an alternative embodiment of the thin-film solar module,the active energy storage layer may comprise a solid electrolyte betweenthe lower electrode and the upper electrode building a super-capacitor.This may be a more simple approach than a complete battery, as discussedbefore. The super-capacitor may also be simple to fabricate.

Based on the battery and the super-capacitor there may also be anembodiment of the thin-film solar module combining the two concepts inthe active energy storage layer, in particular, the super-capacitor andthe battery. This may enhance the flexibility of the thin-film solarmodule. The super-capacitor may function as an electrical energy bufferof the battery, e.g., in cases of a short term high current demand outof the energy storage device.

In one additional embodiment of the thin-film solar module, a seconddielectric layer may be included atop the upper electrode of the energystorage device. This second dielectric layer may function as isolationto a next functional unit. The functional units may be shieldedelectrically against each other.

According to one enhanced embodiment, the thin-film solar module maycomprise a structured first metal layer atop the second dielectriclayer, in particular building at least one gate of the at least onetransistor. It may be a buried gate of a channel that may be built ontop of the so built metal gate. Other components like, e.g., aninductor, may also be built by the structures of the first metal layer.

According to an even more enhanced embodiment of the thin-film solarmodule, a third dielectric layer may be built atop the structured firstmetal layer. This third dielectric layer may also fill areas between thestructures of the structured first metal layer and thus may also be atopthe second dielectric layer. Thus, the structures of the first metallayer may be buried in-between the second and third dielectric layer.

In embodiments of the thin-film solar module, a structured semiconductorlayer may be built atop the third dielectric layer overlapping at leastin parts with structures of the structured first metal layer. This way,in particular, an active channel of the at least one thin-filmtransistor may be built over the already discussed gate.

According to one further embodiment of the thin-film solar module, thestructured semiconductor layer may comprise a semiconductor oxidecompound, in particular amorphous InGaZnO (IGZO) or crystalline IGZO.Amorphous IGZO has high enough electron mobility and may be deposited atnearly room temperature. Thus, its fabrication may not negativelyinfluence lower layers of the thin-film solar device, in particular thecathode and anode regions of the thin-film battery.

According to a further enhanced embodiment of the thin-film solarmodule, there may be a structured second metal layer side-by-side withthe structured semiconductor layer and atop the third dielectric layerconnecting components of the electronic controller through vias to thefront-side electrode of the thin-film solar cell and to the back-sideelectrode of the thin-film solar cell. The second metal layer hasdifferent purposes: by being attached to the elements of thesemiconductor layer, transistors may be formed, and connections betweendifferent transistors, vias and other elements may be established.

According to another embodiment of the thin-film solar module, thesecond metal layer may connect components of the electronic controllerthrough vias to the lower electrode of the thin-film energy storagedevice and the upper electrode of the thin-film energy storage device.This way either the solar cell or the energy storage device may beattached to the electronic controller.

According to a further embodiment of the thin-film solar module, thestructured first metal layer may form an inductor and/or a capacitor.Thus, passive components may be formed within the thin-film deviceenhancing the capabilities of the electronic controller and lowering theproduction cost. These passive components may then also be connected tothe active elements of the electronic controller.

Turning now to the method for manufacturing the thin-film solar module,the building of the thin-film solar cell may comprise depositing atransparent front-side electrode atop a transparent substrate,depositing a photovoltaic layer atop the front-side electrode, anddepositing a back-side electrode (124) onto the photovoltaic layer, soas to form a thin-film solar cell. The photovoltaic layer has alreadybeen described above.

According to a further embodiment of the method, the building thethin-film energy storage device may comprise depositing a firstdielectric layer onto the back-side electrode, depositing a lowerelectrode atop the first dielectric layer, depositing an active energystorage layer atop the lower electrode, which has been described abovealready, and depositing an upper electrode atop the active energystorage layer, so as to form the thin-film energy storage device.

The method may—in one embodiment—also comprise depositing a seconddielectric layer atop of the upper electrode, depositing and structuringa first metal layer atop the second dielectric layer, and forming atleast one out of the group comprising an inductance, a capacitor, and ametal gate of the at least one thin-film transistor.

Furthermore, the method may comprise depositing and structuring a thirddielectric layer atop the structured first metal layer and the seconddielectric layer in areas that the structured first metal layer does notcover. A more of less homogeneous surface may be built. Moreover, themethod may comprise depositing and structuring a semiconductor layeratop the third dielectric layer over the metal gate of the at least onethin-film transistor, forming vias from the top of the third dielectriclayer to the front-side electrode of the thin-film solar cell and to theback-side electrode of the thin-film solar cell (104), and depositingand structuring a second metal layer on top of the just builtsuperstrate configuration building source and drain of the at least onethin-film transistor. This may establish electrical contact to thefront-side electrode of the thin-film solar cell, and to the back-sideelectrode of the solar cell, through vias.

The above-described method may further be enhanced by building vias fromthe top of the third dielectric layer to the lower electrode of thethin-film energy storage device and the upper electrode of the thin-filmenergy storage device. The depositing and structuring of a second metallayer may comprise establishing electrical contact between components ofthe electronic controller and the lower electrode of the thin-filmenergy storage device and the upper electrode of the thin-film energystorage device. Thus, the lower functional unit of the solar module maybe connectable to the electronic controller layer.

Finally, the integrated thin-film device may be sealed by a cover layercomprising a coating with a known dielectric coating material.

It should also be noted that embodiments of the invention have beendescribed with reference to different subject-matters. In particular,some embodiments have been described with reference to method typeclaims whereas other embodiments have been described with reference toapparatus type claims. However, a person skilled in the art will gatherfrom the above and the following description that, unless otherwisenotified, in addition to any combination of features belonging to onetype of the subject-matter, also any combination between featuresrelating to different subject-matters, in particular, between featuresof the method type claims, and features of the apparatus type claims, isconsidered as to be disclosed within this document.

The aspects defined above and further aspects of the present inventionare apparent from the examples of embodiments to be describedhereinafter and are explained with reference to the examples ofembodiments, but to which the invention is not limited.

In the following, a detailed description of the Figures will be given.All instructions in the Figures are schematic. First, an embodiment ofthe inventive thin-film integrated device with a solar cell, anintegrated battery, and a controller is described in general terms.Afterwards, further details and embodiments, as well as the method formanufacturing an integrated device with a solar cell, an integratedbattery, and a controller, will be described.

A metal oxide material known from use in thin-film transistor (TFT)manufacturing, amorphous InGaZnO (a-IGZO), may be used to replace theamorphous or a-Si based technology as transistor dimensions get furtherreduced for better integration and lower energy consumption. A-IGZOmaterial may be used in a metal oxide semiconductor field-effecttransistor (MOSFET) with about 40× higher electron mobility compared toa-Si. Embodiments of the present invention may combine manufacturingmaterials and processes from thin-film solar cells, thin-film batteriesand thin-film transistors to build new solar cell modules integratedmonolithically with power conversion electronics and energy storagedevices. Certain embodiments also use a-IGZO to create TFT devices thatare compatible with thin-film solar cell manufacturing methods.

Embodiments of the invention may take a variety of forms, and exemplaryimplementation details are discussed subsequently with reference to theFigures. The method steps described below do not form a complete processflow for manufacturing thin-film solar cells or modules. Since presentembodiments may be practiced in conjunction with the thin-film solarcell module fabrication techniques, thin-film energy storage devicefabrication techniques, and thin-film transistor fabrication techniquescurrently used in the art, only a limited number of commonly practicedprocess steps are included, as necessary, for an understanding of thedescribed embodiments. The Figures represent cross-section portions of athin-film solar cell during fabrication and are not drawn to scale.Instead the Figures are drawn to illustrate the features of thedescribed embodiments. Specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the methods and structures of the present disclosure.

FIG. 1A shows an embodiment of a thin-film solar module 100, accordingto the disclosed concept. This thin-film solar module 100 comprises anumber of sub modules, such as a thin-film solar cell 104, a thin-filmenergy storage device 106 or thin-film battery, and an electroniccontroller 108. Such a thin-film electronic controller 108 may comprisea series of active and passive electronic components such as transistors110, or more complex electronic circuits like microcontrollerscomprising MPPT circuits.

The thin-film solar cell 104 may be located on a transparent substrate102. Passive and active electronic components of the thin-film solarmodule 100 may be interconnected electrically, either directly by ametal layer 146, or through vias, e.g., vias 148-0, . . . , 148-5 whichmay be located at different positions within the thin-film solar module100. For example, via 148-0 and via 148-2 may connect the layers 120 and124 of the solar cell 104 to the second metal layer 146.

In an alternative configuration of the vias 148, the energy storagedevice 106 may be connected to the second metal layer 146. In this case,the energy storage device 106, in particular the layers 130 and 134 ofthe energy storage device 106, may be connected to the second metallayer 146. The vias 148-4 and 148-5, shown in FIG. 1B, may connect theenergy storage device 106 to the electronic controller 108. In bothcases (FIG. 1A and 1B), vias 148-1 and 148-3 contact the inductor 702(shown in FIG. 7) to the second metal layer 146 and become a componentof the electronic controller 108.

From the concept discussed with respect to FIG. 1A and 1B, a skilledperson may understand that two electronic controllers 108 may beconfigured within the electronic controller layer 108. The differentfunctions may be achieved by different vias.

Thus, the thin-film solar module may comprise—beside intermediatelayers, like the first dielectric layer 128 or the second dielectriclayer 138—three active compound layers: the thin-film solar cell 104,the thin-film energy storage device 106, and an electronic circuitry inform of an electronic controller 108. It may be noted that all threeactive compound layers may be manufactured by one integrated thin-filmmanufacturing process. None of the three active compound layers may beprefabricated or delivered independently to produce the thin-film solarmodule. Instead, all the required layers as shown in FIG. 1A and 1B,alongside with intermediate layers, are fabricated in one thin-filmfabrication process.

A group of thin-film solar modules 100 may be linked togetherelectrically to form a larger, more powerful solar module (see, e.g.,FIG. 9).

Potential steps for an exemplary embodiment of a method formanufacturing the thin-film solar module 100 including at least onetransistor 110, passive electronic components like an inductor and/or acapacitor, as well as a thin-film solar cell on a substrate 102, may nowbe described using the following schematic illustrations. Although FIGS.1A, 1B show more than one transistor, only one has been encircled todemonstrate the concept.

FIG. 2 shows a substrate 102 upon which an embodiment of the presentinvention may be fabricated. The substrate 102 may comprise anon-conducting, transparent carrier element like soda-lime glass or apolyimide film having a thickness of 1 to 3 mm In another embodiment,substrate 102 may be a flexible sheet of steel foil. A front-sideelectrode 120 may be deposited on the substrate 102. The front-sideelectrode 120 may comprise metal or a transparent conductive oxide(TCO). TCO materials may comprise, e.g., a zinc oxide (ZnO), tin oxide(SnO₂), tin doped indium oxide (ITO) or, indium oxide (In₂O₃). Metalmaterials for the electrode may comprise, e.g., Mo, Cu, Al, Ag or othersuitable metals or alloys.

On top of the transparent front-side electrode 120, a photovoltaic layer122 may be deposited. Atop the photovoltaic layer 122, a backsideelectrode 124 may be deposited. It may be a metallic conductive layerwhich also serves as a reflector to reflect most common absorbed lightback into the photovoltaic layer 122 of the thin-film solar cell 104. Itmay be noted that the light may enter the thin-film solar cell 104 viathe transparent substrate 102 and the transparent front-side electrode120. It may also be noted that the front-side electrode 120 of thethin-film solar cell 104 may be longer than the back-side electrode 124of the thin-film solar cell 104. This may allow an easy connection tolayers above the thin-film energy storage device 106 through vias 148.The photovoltaic layer 122 may be the active layer of the solar cell.

The thin-film solar cell 104 may be covered by a deposited firstdielectric layer 128. This may be any isolating material like, e.g.,Al₂O₃ or SiO₂, or comparable dielectric material.

Atop the first dielectric layer 128, a lower electrode 130 of the energystorage device 106 may be deposited. Any known deposition technique forthin-film devices may be used. The lower electrode 130 may be a metal ora conductive metal oxide, as mentioned above.

As next layer, an active energy storage layer 132 may be deposited onthe lower electrode 130. A second electrode for the thin-film energystorage device 106, an upper electrode 134, may be deposited atop theactive energy storage layer 132. The lower electrode 130 and the upperelectrode 134 may function as thin-film battery anode and thin-filmbattery cathode or vice versa. It may be noted that for structuring thedifferent layers, known masking techniques using photo-resist andsuitable etching processes may be used.

It may also be noted that the thin-film energy storage device 106 may bemanufactured based on, e.g., a Lithium-metal cathodes and solidelectrolytes with their beneficial properties in terms ofminiaturization, as known by a skilled person. Thin-film lithiumbatteries offer high power density. As demonstrated here, thin-filmbatteries offer the potential for integration with other thin-filmfunctional elements. The advantages of positioning the thin-film battery106 between the other functional layouts, i.e., the thin-film solar cell104 and electronic components of electronic controller 108 manufacturedin the thin-film process have been described above already.

The resulting thin-film energy storage device 106 may be covered with asecond dielectric layer 138, thereby integrating the thin-film storagedevice. Again, the second dielectric layer 138 may comprise anyisolating material like, e.g., Al₂O₃ or SiO₂.

Referring to FIG. 3, a first metal layer 140 may be deposited andstructured on the second dielectric layer 138. It may be noted thatalthough the thin-film solar cell 104 as well as the thin-film energystorage device 106 have metal layers, i.e., 120, 124, 130, 134, thenumbering for the subsequent metal layers may only refer to the thirdfunctional device, the electronic controller 108. The depositing andespecially the structuring of the first metal layer may again beperformed using well known semiconductor fabrication processes usingphoto-resists masks and material removal processes, e.g., etching.

The structures of the first metal layer 140 atop the second dielectriclayer 138 may cover an area above the upper electrode 134 of thethin-film energy storage device 106. However the structures of the firstmetal layer 140 may extend beyond the limits of the thin-film energystorage device 106. In order to manufacture a compact thin-film solarmodule, it may be advantageous to limit the structures of the firstmetal layer to the dimension of the underlying functional devices, i.e.,the thin-film solar cell 104 and the thin-film battery 106.

The structures 140 of the first metal layer 140 may—in combination withadditional layers—be elements like an inductor (see below), a gate of atransistor, or components of other electric or electronic devices.Several such components may be structured in this metal layer, buildingan independent electronic controller afterwards.

The structures of the first metal layer 140 may be covered with a thirddielectric layer 142, as described in FIG. 4. The third dielectric layer142 may cover the structures of the first metal layer 140 and may alsofill the space between the structures 140 of the first metal layer 140.It may be noted that the second and third dielectric layer may be shownas separated by a dashed line. However, the two dielectric layers maynot have a real interface because they may be composed of the samedielectric material.

As the next fabrication step, semiconductor material 144 may bestructurally deposited atop the third dielectric layer 142. Again, knownmasking and structuring techniques may be used. Some of thesemiconductor material structures 144 may be positioned above one ormore structures 140 of the second metal layer which may later-onpartially function as a gate of a MOSFET 110. In such a configuration,the semiconductor structures 144 may function as a channel or activelayer of the related MOSFET 110. A semiconductor material 144, inparticular, amorphous InGaZnO (a-IGZO) or crystalline IGZO, may be used.

In order to establish electrical contact to lower layers of thethin-film solar module, vias 148 may be built into thethree-dimensional, superstrate structure of the thin-film solar module100, as depicted in FIG. 5. Examples of other vias 148 and theirconnections are shown in FIG. 6. The vias 148-4, 148-5 may buildconnections from the top of the three-dimensional thin-film device asmanufactured so far to lower conducting layers, like, e.g., the lowerelectrode 130 and the upper electrode 134 of the energy storage device106.

Vias 148-0, 148-2 may build connections from the top of thethree-dimensional thin-film device as manufactured so far to thefront-side electrode 120 and the back-side electrode 124 of the solarcell 104, as well as to individual structures 140 of the first metallayer 140. The vias 148-x may selectively be built with isolatingsidewalls where appropriate. This is, e.g., shown for the second via148-5 in FIG. 5 reaching from the surface of the third dielectric layer142 through the upper electrode 134 of the thin-film energy storagedevice 106 to the lower electrode 130 of the same functional device 106,the energy storage device 106.

The via 148-3 may, e.g., be a middle connector of a coil or inductorbuilt of loops or turns in the structured first metal layer (cf. FIG.8). The structures 150 may depict a cross-section of turns of such aninductor 702 (shown in FIG. 7). Such an inductor may be an example of apassive electric element as part of the electronic controller 108. Also,capacitor plates may be integrated in between the second and the thirddielectric layer. A second plate for a capacitor may be included in thesecond metal layer 146.

Referring now to FIG. 6, in addition, a second metal layer 146 is shown.FIG. 6 depicts an upper portion of the thin-film solar module 100. Thesecond metal layer 146 may be structured, as exemplarily shown. Again,known depositing and structuring techniques may be used for the coveringsecond metal layer 146. As shown, the second metal layer 146 connects tothe vias 148-4 and 148-5, and may connect to side portions of thestructures 144 of the semiconductor layer 144. If, e.g., elements of thesecond metal layer 146 may connect electrically and mechanically tosides of the semiconductor structure 144, the semiconductor structure144 may build a channel of a transistor, e.g., transistor 110, in whichstructures 140 of the first metal layer 140 function as a gate of such atransistor 110. This way, a third functional unit, namely, elements ofthe electronic controller 108 may be built as part of the integratedthin-film solar module.

Additional semiconductor components, i.e., active electronic devices aswell as passive electrical components, may be monolithically integratedin the electronic controller 108. Also these elements may advantageouslybe built as part of the thin-film manufacturing process. The electroniccontroller may, e.g., include MPPT components and/or DC-DC or DC-ACconverters. Different functional modes of the controller have alreadybeen discussed above.

Another layer may cover the complete superstrate configuration of thethin-film solar module protecting it from outside environmentalinfluences. Materials for a sealing layer are known to a skilled person.

It may be noted that the thin-film battery 106 may be a stack ofthin-film batteries. It may also be noted that not just one thin-filmsolar cell 104 may be connected to electronic controller 108. Instead, aseries of thin-film solar cells 104 may be connectable to the electroniccontroller 108 and/or the battery 106. This way, any combination ofnumbers of thin-film solar cells 104 and thin-film batteries 106 may becombined with any suitable kind of electronic components as part of theelectronic controller 108.

FIG. 7 illustrates control circuitry 700 to shape an output waveform ofthe solar cell 104, in accordance with an embodiment of the presentinvention. The control circuitry may be realized by the electroniccontroller 108. Circuit 700 shows an electrical circuit diagram as partof the device 100 of FIG. 1A or 1B comprising wiring, the solar cell 104or alternatively, the energy storage device 106, four transistors 704,706, 708, and 710, an inductor 702, and a capacitor 712. The transistors704, 706, 708, and 710 may act as switches to change the circuitconnection of the solar cell 104 or the energy storage device 106selectively to the DC bus 720. The circuitry 700 may also be used totransform the output voltage of either the solar cell 104 oralternatively, the energy storage device 106 to a level appropriate tothe DC bus 720. It may be noted that the connection of either the solarcell 104 or alternatively the energy storage device 106 to the controlcircuitry 700 may depend on the vias, as discussed above.

FIG. 8 shows a symbolic view onto the second metal layer 146. Alsoillustrated are connections to transistors 704, 706, 708 and 710.Symbolically, lines are drawn to these transistors symbolizingconnections to the gates G1, G2, G3, and G4 of these transistors as partof the first metal layer. The via 148-3 is shown as a 2-dimensionalequivalent connecting to the middle connector of the Inductor 702. Atthe other end of the inductor 702, via 148-1 is shown. Also visible arethe vias 148-0 and 148-2. From the via 148-2, a ground line is drawn tothe DC bus 720. On the other end, the positive output of the showncircuitry delivers a positive voltage at 814, which may also beconnected to the DC bus 720.

FIG. 9 shows an extended solar module 900 comprising a series of solarcell modules 100 and electronic controllers. On the left side, a seriesof energy storage devices 106-1, 106-2, . . . , 106-n are connected tocharger/discharger DC/DC circuits 902, which may have the form asdiscussed in the context of FIG. 7. The energy storage devices 106-1,106-2, . . . , 106-n are connected via a series of circuits 902 to theDC bus 720.

On the right side of FIG. 9, a series of solar cells 104-1, 104-1, 104-nare connected via DC/DC MPPT circuits 904 to the DC bus 720. Thecircuits 904 may have the form as discussed in the context of FIG. 7.The function of the circuits 902 as well as the function of the circuits904 may be controlled by the controller 906. The controller 906 may alsobe integrated into the electronic controller 108, as discussed in thecontext of FIGS. 1A and 1B. The controller 906 may also influence aDC/AC converter 908 which may take the signals of the DC bus 720 asinput in order to generate an AC output 910. Both, the controller 906and the DC/AC converter 908 may optionally be part of the electroniccontroller 108.

FIG. 10 shows a configuration 1000 of two combined solar modules 100.This figure shows the two combined solar modules having each a solarcell layer 104, an energy storage device layer 106 and an electroniccontroller layout 108. Both solar modules 100 have the transparentfront-side electrode 120 in common. The back-side electrodes 124 of thesolar cells 104, as well as the lower electrodes 130 and the upperelectrodes 134 of the energy storage devices 106 of the two side-by-sideconfigured solar modules 100 are not connected to each other. This way,one of the solar modules 100—e.g., the left one—may have an electroniccontroller layer 108 with vias 148 according to FIG. 1A, whereas theother solar module 100—e.g., the right one—may have an electroniccontroller layer with vias according to FIG. 1B.

While the invention has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments may be devised, whichdo not depart from the scope of the invention, as disclosed herein.Accordingly, the scope of the invention should be limited only by theattached claims. Also, elements described in association with differentembodiments may be combined.

The corresponding structures, materials, acts, and equivalents of allmeans or steps plus function elements in the claims below are intendedto include any structure, material, or act for performing the functionin combination with other claimed elements, as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skills in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skills in the art to understand the invention forvarious embodiments with various modifications, as are suited to theparticular use contemplated.

For purposes of the description herein, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, andderivatives thereof shall relate to the disclosed structures andmethods, as oriented in the drawing Figures. The terms “overlying”,“atop”, “over”, “on”, “positioned on” or “positioned atop” mean that afirst element is present on a second element wherein interveningelements, such as an interface structure, may be present between thefirst element and the second element. The term “direct contact” meansthat a first element and a second element is connected without anyintermediary conducting, insulating or semiconductor layers at theinterface of the two elements.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to limit the invention. As usedherein, the singular forms “a”, “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It may be further understood that the terms “comprises” or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, or components,but do not preclude the presence or addition of one or more otherfeatures, integers, steps, operations, elements, components, or groupsthereof.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations may be apparent to those of ordinary skillsin the art without departing from the scope and spirit of the describedembodiments. Thus, the present invention is not limited to theembodiments shown, but is to be accorded the widest scope consistentwith the principles and features disclosed herein.

What is claimed is:
 1. A method for manufacturing a thin-film solarmodule in a superstrate configuration, the method comprising:fabricating a thin-film solar cell, having at least one solar diode on atransparent substrate at a first temperature; fabricating a thin-filmenergy storage device after the thin-film solar cell at a secondtemperature; fabricating an electronic controller, comprising at leastone thin-film transistor, above the thin-film energy storage device;fabricating an oxide semiconductor at room temperature on top of thethin-film energy storage device after the fabricating of the thin-filmenergy storage device: and providing electrical connections between theelectronic controller and the thin-film solar cell by a first set ofvias, wherein the electronic controller is electrically connected to thethin-film energy storage device by a second set of vias, wherein thefirst set of vias extends through at least the thin-film energy storagedevice.
 2. The method according to claim 1, wherein fabricating thethin-film solar cell comprises: depositing a transparent front-sideelectrode atop the transparent substrate; depositing a photovoltaiclayer atop the front-side electrode; and depositing a back-sideelectrode onto the photovoltaic layer so as to form the thin-film solarcell.
 3. The method according to claim 2, wherein fabricating thethin-film energy storage device comprises: depositing a first dielectriclayer onto the back-side electrode; depositing a lower electrode atopthe first dielectric layer; depositing an active energy storage layeratop the lower electrode; and depositing an upper electrode atop theactive energy storage layer so as to form the thin-film energy storagedevice.
 4. The method according to claim 3, wherein fabricating theelectronic controller comprises: depositing a second dielectric layeratop of the upper electrode; depositing and structuring a structuredfirst metal layer atop the second dielectric layer, forming at least oneout of the group comprising an inductor, a capacitor, and a metal gateof the at least one thin-film transistor; depositing and structuring athird dielectric layer atop the structured first metal layer and thesecond dielectric layer in areas the structured first metal layer doesnot cover; depositing and structuring a semiconductor layer atop thethird dielectric layer and positioned over the metal gate of the atleast one thin-film transistor; building the first set of vias from thetop of the third dielectric layer to the front-side electrode of thethin-film solar cell and to the back-side electrode of the thin-filmsolar cell; and depositing and structuring a second metal layer atop thethird dielectric layer, forming a source and drain of the at least onethin-film transistor and establishing contact to the front-sideelectrode of the thin-film solar cell and to the back-side electrode ofthe thin-film solar cell through the first set of vias.
 5. The methodaccording to claim 4, further comprising building the second set of viasfrom the top of the third dielectric layer to the lower electrode of thethin-film energy storage device and to the upper electrode of thethin-film energy storage device, wherein depositing and structuring thesecond metal layer comprises establishing electrical contact betweencomponents of the electronic controller, the lower electrode of thethin-film energy storage device, and the upper electrode of thethin-film energy storage device.
 6. The method according to claim 4,further comprising: forming the inductor within the first metal layer;and forming a third set of vias through the third dielectric layer byetching the third dielectric layer; wherein the third dielectric layeris etched selectively to enable a connection of the inductor to thesecond metal layer.
 7. The method according to claim 1, wherein thefirst temperature is higher than the second temperature.